Impact of design and operating parameters on the thermal performance of heat pipes:A review

The goal of this research is to review how different technologies have affected heat pipes' thermal performance and critically evaluate the progress that has been made in this area. Heat pipe's thermal efficiency has been greatly improved because of the implementation of novel approaches proposed by some researchers. Manufacturing various forms of grooves, inner surface treatment, manufacturing different types of fins, using embedded heat pipes, producing rough inner surfaces, utilizing nanofluid as a working fluid, using a non-condensable gas, etc. are some of the primary ways mentioned and examined. Researchers in this field have found that heat pipe efficiency might be improved by the use of the aforementioned strategies; however, some of these approaches have practical limitations. These researchers have a good understanding of how to optimize the change settings for the best optimization outcomes and can help us choose which technique to use in a particular scenario. This paper presents an experimental and numerical review of studies related to the behavior of heat pipes to understand how they affect thermal performance through a change in configuration, structure, design, and operating parameters. “Overall, the results of the published works show that the improving of the efficiency of the heat pipes by applying different techniques: 1) enhancement of the design parameters (like filling ratio, tilt angle, type of working fluids, and dimensions of the heat pipes), 2) modified configurations (like inserts fins, grooved, by-pass line between evaporator and condenser, roughness of the inner surface, utilized tiny pillars, corrugated configuration portion in the evaporator, and adding a vortex alternator), 3) using different nano-fluids as working fluids, and 4) hybrid heat pipes is (31.8–75%), (12.4%−35.5%), (16–87.2%), and (53% −86.7%), respectively.

Numerical and experimental investigation for analyzing the temperature influence on the performance of photovoltaic module

The effect of temperature is considered a significant factor in controlling the output voltage of the photovoltaic (PV) module. In this work, a numerical analysis with an experimental demonstration were investigated to analyze the temperature effect on the performance of PV module. In the numerical part, the current-voltage I-V and power-voltage P-V curves of the PV module were simulated under the influence of various module temperature ranged from 25 to 65 ℃ as well as various solar radiation from 200 to 1000 W/m2. In addition, the variation of PV output electrical characteristics with a module temperature were performed to analyze the temperature coefficients of the PV module. Moreover, the experimental demonstration was performed to analyze performance of the PV module under the real weather conditions of Iraq. The numerical results conclude that the maximum power was recorded 165 W at 1000 W/m2 solar irradiance and 25 ℃ PV module temperature. Furthermore, the temperature coefficient was recorded a maximum value with output power about (−0.26) %/℃. Besides, the experimental results show that the maximum power was recorded 131.2 W at solar irradiance about 920 W/m2

Impact of design and operating parameters on the thermal performance of heat pipes:A review

The goal of this research is to review how different technologies have affected heat pipes' thermal performance and critically evaluate the progress that has been made in this area. Heat pipe's thermal efficiency has been greatly improved because of the implementation of novel approaches proposed by some researchers. Manufacturing various forms of grooves, inner surface treatment, manufacturing different types of fins, using embedded heat pipes, producing rough inner surfaces, utilizing nanofluid as a working fluid, using a non-condensable gas, etc. are some of the primary ways mentioned and examined. Researchers in this field have found that heat pipe efficiency might be improved by the use of the aforementioned strategies; however, some of these approaches have practical limitations. These researchers have a good understanding of how to optimize the change settings for the best optimization outcomes and can help us choose which technique to use in a particular scenario. This paper presents an experimental and numerical review of studies related to the behavior of heat pipes to understand how they affect thermal performance through a change in configuration, structure, design, and operating parameters. “Overall, the results of the published works show that the improving of the efficiency of the heat pipes by applying different techniques: 1) enhancement of the design parameters (like filling ratio, tilt angle, type of working fluids, and dimensions of the heat pipes), 2) modified configurations (like inserts fins, grooved, by-pass line between evaporator and condenser, roughness of the inner surface, utilized tiny pillars, corrugated configuration portion in the evaporator, and adding a vortex alternator), 3) using different nano-fluids as working fluids, and 4) hybrid heat pipes is (31.8–75%), (12.4%−35.5%), (16–87.2%), and (53% −86.7%), respectively.

Comparative Study of In Situ Loaded Antibody and PEG‐Fab NIPAAM Gels

Hydrogels can potentially prolong the release of a therapeutic protein, especially to treat blinding conditions. One challenge is to ensure that the protein and hydrogel are intimately mixed by better protein entanglement within the hydrogel. N-isopropylacrylamide (NIPAAM) gels are optimized with poly(ethylene glycol) diacrylate (PEDGA) crosslinker in the presence of either bevacizumab or PEG conjugated ranibizumab (PEG10-Fabrani). The release profiles of the hydrogels are evaluated using an outflow model of the eye, which is previously validated for human clearance of proteins. Release kinetics of in situ loaded bevacizumab-NIPAAM gels displays a prolonged bimodal release profile in phosphate buffered saline compared to bevacizumab loaded into a preformed NIPAAM gel. Bevacizumab release in simulated vitreous from in situ loaded gels is similar to bevacizumab control indicating that diffusion through the vitreous rather than from the gel is rate limiting. Ranibizumab is site-specifically PEGylated by disulfide rebridging conjugation. Prolonged and continuous release is observed with the in situ loaded PEG10-Fabrani-NIPAAM gels compared to PEG10-Fabrani injection (control). Compared to an unmodified protein, there is better mixing due to PEG entanglement and compatibility of PEG10-Fabrani within the NIPAAM-PEDGA hydrogel. These encouraging results suggest that the extended release of PEGylated proteins in the vitreous can be achieved using injectable hydrogels

Development and performance of concentrated optical water filter for photovoltaic applications

New Concentrated Optical Water Filter (COWF) for Photovoltaic (PV) applications is investigated. The COWF is placed in front of the PV module in order to reduce the thermal load on the PV. The COWF acts as a spectrum splitter to absorb the unwanted radiation and convert it to heat, and allow the useful radiation to reach the PV. The COWF consists of two parts; Optical Water Filter (OWF) and V-trough Solar Concentrator (VTSC). The OWF consists of two glass panels with specific gab filled with water which flows carrying away the heat and preventing it from reaching the PV. However, the disadvantage of using the OWF with PV is some reduction in the electrical power output of the PV due to optical losses. Therefore, VTSCs are developed to be integrated with OWF to overcome the optical losses. The VTSC consists of two reflectors placed as a (V) letter in front of the OWF in order to increase the solar radiation received by the PV to overcome the optical losses by the OWF. Overall, it can be concluded that COWF can enhance the electrical performance of the PV and reduce the PV temperature simultaneously relative to the PV module without COWF

Comprehensive Review of Dust Properties and Their Influence on Photovoltaic Systems: Electrical, Optical, Thermal Models and Experimentation Techniques

As conventional energy sources decrease and worldwide power demand grows, the appeal of photovoltaic (PV) systems as sustainable and ecofriendly energy sources has grown. PV system installation is influenced by geographical location, orientation, and inclination angle. Despite its success, weather conditions such as dust substantially influences PV module performance. This study provides a comprehensive review of the existing literature on the impact of dust characteristics on PV systems from three distinct perspectives. Firstly, the study looks at the dust properties in different categories: optical, thermal, physical, and chemical, highlighting their significant impact on the performance of PV systems. Secondly, the research reviews various approaches and equipment used to evaluate dust’s impact on PV, emphasizing the need for reliable instruments to measure its effects accurately. Finally, the study looks at modeling and predicting the influence of dust on PV systems, considering the parameters that affect electrical, optical, and thermal behavior. The review draws attention to the need for further research into dust’s properties, including thermal conductivity and emissivity. This analysis highlights the need for further research to develop a scientific correlation to predict the thermal behavior of PV in dusty environments. This paper identifies areas for further research to develop more efficient and effective methods for analyzing this influence and improving PV efficiency and lifespan

Effect of Local Floor Heating System on Occupants’ Thermal Comfort and Energy Consumption Using Computational Fluid Dynamics (CFD)

In this article, the influence of splitting a local underfloor air distribution system (UFAD) on indoor thermal comfort for three occupants was studied numerically. A validated computational fluid dynamics (CFD) model was employed in this investigation. The proposed heating system was evaluated and analyzed for different values of air temperature and supply velocity. Providing suitable thermal comfort and saving energy are considered the main evaluation indexes for this study. Three cases, cases 2, 3, and 4, of the proposed local UFAD system were compared with a traditional heating system case, case 1. The supplying air velocity and air temperature in the reference case were 0.5 m/s and 29 °C, while in cases 2, 3, and 4, they were 0.4 m/s and 29 °C, 28 °C, and 27 °C, respectively. The results show that acceptable indoor human thermal comfort and energy demand reduction were achieved by using the splitting UFAD concept